EP0195360B1 - Atmospheric gas burner - Google Patents

Abstract

An atmospheric gas burner assembly comprises a burner tube defining a multiplicity of gas outlet ports and an element reducing the flame temperature and, hence, the emission of oxides of nitrogen disposed above the burner tube in the flame area. To optimize the reduction of NOx emission without affecting permitted CO values and to render the values of reduction in NOx emissions largely independent of the geometry of the surrounding combustion chamber so as to obtain reproducible emission reduction values, the reducing element is constituted by a multiplicity of fins confining the flames in shafts extending therebetween, the fins extending perpendicularly above the tube and being distributed along the tube.

Description

The invention relates to an atmospheric gas burner according to the preamble of the main claim.

Elements arranged above or on the burner tube, which, however, have nothing to do with a NOX reduction, are known from EP-A-0 139 353 and from GB-A-1 038 216.

In the burner according to EP-A-0 139 353, fins are arranged next to each outflow opening on the burner tube, which are formed from more or less large sheets with bends at the upper free end, these sheets being used only for gas / air mixing and flame stabilization.

It is not possible to cool the flame.

Such flame cooling is also not achievable with the burner according to GB-A-1 038 216, since the element arranged above the burner tube is a box-shaped structure with an open top that extends almost over the entire length of the burner tube long slot in the bottom, which is followed by a funnel-shaped inflow nozzle directed downwards against the row of outflow openings and through which air is to be supplied to the flame to an increased extent.

With regard to the so-called NOX emission from heating systems which are operated with oil or gas burners, reference is made to "Warmth-Gas-international", Volume 30 (1981), No. 1, pages 41, 42. The general environmental pollution problems also arise The question of so-called NOX emissions in the heating system area came up for discussion with the aim of reducing NOX emissions as much as possible. Suggestions for this consist in shielding the burner tubes on the flame side with a fine-mesh metal fabric in order to cool the flame and to radiate the heat absorbed by the element that reduces NOx formation. For oil burners, the article mentioned includes a reducing element with a hemispherical, perforated shell. In particular in the case of atmospheric gas burners, it has been found that such installations or flame screens prevent this. can that the oxygen from the supplied secondary air can come into direct contact with the high flame temperature, and that this leads to a reduction in NOx formation. At the same time, however, it can be observed that if the element disturbs the flame in an unfavorable manner, then the combustion process is no longer complete and thus the CO formation rises, apart from the fact that with such simple shields with regard to the NOX reduction apparently by far the maximum possible dimension cannot be achieved, presumably not because the flames are cooled too little. As far as could be determined, this is also related to the geometry of the combustion chamber walls surrounding the burner tube and also to the geometry of the elements introduced in the hottest flame areas which are intended to reduce NOX formation.

The invention is therefore based on the object of improving an atmospheric gas burner of the type mentioned in such a way that optimal NOX reduction values are to be obtained and that the reduction is also to be largely independent of the surrounding geometry, i.e. the NOX reduction should be reproducible on practically every boiler equipped with an atmospheric gas burner.

This object is achieved with an atmospheric gas burner of the type mentioned by the features stated in the characterizing part of the main claim. Advantageous further developments result from the subclaims.

With this burner designed according to the invention, it has surprisingly been found that, compared to the elements mentioned and known at the outset, there was a substantially improved reduction in NOx, which is largely independent of the respective surrounding geometry of the combustion chamber, without an increase in CO Education can be observed. This can basically only be explained by the fact that the combustion process remains largely undisturbed due to the special shape of the reducing element, the elements in the form of lamellae apparently have sufficiently large, heat-radiating surfaces, which are also adequately cooled due to the special design, since Secondary air can flow in between the fins, as a kind of chimney effect occurs between the fins.

In one embodiment of the burner, the floors, which are advantageously rounded into the lamellae of the pocket-like body, are designed in a shape that is adapted to the curvature of the burner tube in the transverse assignment of the pocket-like bodies to the burner tube, so that the bottoms of the bodies have the same distance to the burner tube at every point. When the pocket-like bodies are longitudinally assigned to the burner tube, which then correspond approximately to the length of the burner tube, but can also be arranged shorter in a row as sections, the bodies forming the reducing element are arranged with their bottoms equally spaced from the surface of the burner tube.

It is also advantageously provided that the pocket-like bodies are arranged at a distance from one another which corresponds to their width, i.e. the area above the burner tube which is actually spatially occupied by the bodies is only about half of the total area occupied by flames.

As a rule, the burner openings in the burner tubes are evenly spaced apart standing groups are arranged, the pocket-like bodies are advantageously arranged over the opening-free areas of the burner tube.

Since, according to the invention, the reducing element consists of a plurality of such individual bodies, these are expediently arranged together on at least one carrier which is furthermore arranged such that it can be adjusted in a variable distance with respect to the burner tube, which provides a further possibility for optimizing the NOX reduction, with which possibility the fact is taken into account that the gases used can have different compositions, which may require different distance settings of the reducing element to the burner tube.

Since, as mentioned, such pocket-shaped bodies can also be arranged in the longitudinal direction, that is to say parallel to the longitudinal axis of the burner tube, with a corresponding length dimensioning, such bodies are then advantageously provided in their bottoms with air inflow openings in order to ensure the aforementioned chimney effect even with such relatively long bodies.

The atmospheric gas burner according to the invention is explained in more detail below with the aid of exemplary embodiments.

• Fig. 1 eine Seitenansicht eines Brennerrohres;
• Fig. 2 eine Draufsicht auf das Brennerrohr;
• Fig. 3 eine Vorderansicht des Brennerrohres nach Fig. 1;
• Fig. 4 eine Seitenansicht des Brennerrohres mit zu taschenartigen Körpern ausgebildeten Lamellen;
• Fig. 5 eine Draufsicht auf das Brennerrohr gemäß Fig. 4;
• Fig. 6 eine Draufsicht auf das aus den einzelnen Körpern nach Fig. 4, 5 gebildete reduzierende Element;
• Fig. 7 eine Ansicht des reduzierenden Elementes in Pfeilrichtung A gemäß Fig. 6 in Anordnung am Brennerrohr und
• Fig. 8 eine Draufsicht auf das Brennerrohr in anderer Ausführungsform.

It shows schematically

• Figure 1 is a side view of a burner tube.
• Fig. 2 is a plan view of the burner tube;
• Fig. 3 is a front view of the burner tube of Fig. 1;
• FIG. 4 shows a side view of the burner tube with fins designed to be pocket-like bodies; FIG.
• FIG. 5 shows a plan view of the burner tube according to FIG. 4;
• 6 shows a plan view of the reducing element formed from the individual bodies according to FIGS. 4 and 5;
• Fig. 7 is a view of the reducing element in the direction of arrow A of FIG. 6 in arrangement on the burner tube and
• Fig. 8 is a plan view of the burner tube in another embodiment.

As can be seen from FIGS. 1, 2, the atmospheric gas burner consists of at least one burner tube 2 with a plurality of gas outflow openings 1 arranged in groups 6, the elements which reduce the flame temperature and thus the NOX formation being arranged in the flame region above the burner tube 2 . For the sake of simplicity, FIGS. 1, 2 show different forms of formation and arrangement of the individual parts forming the reducing element, ie, in the actual embodiment, the reducing element is always formed from the same individual parts, which are basically perpendicular to one another at a distance from one another Above the area of the burner tube 2 containing the gas outlet openings 1, there are lamellae 3 which delimit flame shafts 4 and which, as shown and oriented to the normally given arrangement of the gas outlet openings 1, are preferably arranged transversely to the longitudinal axis of the burner tube. This simplest embodiment is illustrated in the middle area of the burner tube in FIG. 1. With reference to FIG. 3, the fins 3 are cut following the curvature of the burner tube 2. Unless other brackets are provided for the slats 3, small feet 3 'on the slats ensure a corresponding spacing. As can also be seen from FIGS. 1 to 3, two slats 3 with side walls 7 are advantageously and preferably combined to form a shaft box 8, these boxes 8 each above an opening group 6 (on the right in FIGS. 1, 2) or between two opening group 6 (left in Fig. 1, 2) can be arranged above the burner tube 2. This training as a shaft box 8 has the advantage that the lamellae 3 experience stiffening and are therefore less subject to warping due to the action of heat. In addition, of course, the effort required to attach the fins 3 to the burner tube is considerably reduced in comparison to the attachment of individual fins 3. 3 serving as fastening and holding elements side walls 3 can optionally be perforated in the vicinity of the burner tube 2 and provided in the fastening area with elongated holes for which small stud bolts are dotted on the burner tube, so that the boxes 8 with respect to their lower edges 5 Burner tube 2 can be fixed at variable distances.

In this preferred embodiment, the boxes 8 (on the right in FIGS. 1, 2) themselves form the flame shafts 4, while in an arrangement of the boxes 8 between groups of openings (on the left in FIGS. 1, 2) the flame shafts 4 are each delimited by two boxes 8 . Irrespective of whether the boxes 8 are now arranged directly above an opening group 6 or between two opening groups 6, corresponding shafts are created by arranging the boxes 8 next to one another. Even with a group arrangement and configuration, as shown in FIGS. 1, 2, the fins 3 could of course also be oriented parallel to the longitudinal burner tube, i.e. in rows one behind the other and next to one another, with relatively short fins being preferred due to the risk of warping.

In the embodiments according to FIGS. 4 to 8, the reducing element is formed from a plurality of pocket-like bodies 9, which are arranged at the sides and open at the top and are distributed over the gas outflow openings 1 of the burner tube 2, the ends 10 of which advantageously merge into the lamellae when arranged transversely to the burner tube 2 are also adapted in shape to the curvature of the burner tube 2. Such bodies 9 can be easily made of suitable metallic material with appropriate molding tools in one Pull operation. Since, taking into account the usual lengths of burner tubes 2, at least about ten such bodies 9 must be assigned to each burner tube, the whole is formed into a uniformly attachable element, with the aid of two side supports 13, as can be seen in FIGS. 6, 7. An individual holder in the sense of the previously described boxes 8 of the pocket-like bodies 9 would, however, also be possible. The carriers 13 are fastened to the burner tube 2 in a suitable manner and as indicated in FIG. 7, for example, so that the bodies 9 with their bottoms 10 are arranged at a certain distance above the tube 2.

This attachment is preferably and advantageously also adjustable, so that the entire structure can be adjusted with the optimum distance from the burner tube 2. The bodies 9 are expediently arranged at the same distance from one another on the burner tube 2 or on the supports 13. Since the gas outflow openings 1 are usually provided on such burner tubes 2, as also shown in FIGS. 4, 5 and as mentioned above, in groups 6, the pocket-like bodies 9 are advantageously arranged above the opening-free areas of the burner tube 2, since this Flames standing above the gas outflow openings 1 are least disturbed. The flames burn freely in the spaces between two bodies 9, which in turn, since they are open on the side (see flow arrow in Fig. 7), are open to the lateral inflow of secondary air, which thereby cools the fins 3, so that the latter continuously remove heat from the hot flame area, which counteracts NOX formation.

Of course, it is also possible to dimension the bodies 9 accordingly long and to arrange them parallel to the longitudinal extension of the burner tube, as indicated in FIG. 8. Apart from the fact that the body 9 could also be arranged in the form of a number of short pieces in a row in the longitudinal direction in such an arrangement, but this requires a greater amount of support, in the embodiment according to FIG. 8 the bodies 9 have air inlet openings advantageously in the bottoms 10 11, for example in the form of slots, in order to achieve the cooling "chimney effect" within the body 9 in this embodiment as well. Appropriate shaping of the holder 13 also ensures in this embodiment that the bottoms 10 of all the longitudinally extending bodies 9 are at the same distance from the surface of the burner tube 2.

With regard to the described and special embodiments of the NOX-reducing element, there is nothing to prevent the gas outflow openings 1 on the burner tube 2 from the outset from being oriented in terms of their group arrangement to the shape and the course of the fins 3, which, moreover, also in the form of a rough one rastered lamellar grid can be provided, whereby for long lamellae, for example in the sense of FIG. 8, material that warps or only a little warping (thin ceramic lamellae) would expediently be used.

Claims (13)

1. Atmospheric gas burner, consisting of at least one burner pipe (2) with a plurality of gas exit ports (1), with elements in the form of fins (3) which reduce the flame temperature and hence the formation of NOX disposed above the burner pipe (2) in the flame area, characterised in that, the gas exit ports (1) of a burner pipe (2) are assembled in groups (6), each pair of fins (3) define a flame shaft (4) and the fins (3) which define the shaft are disposed above a group (6) or between two groups (6) in the burner pipe (2).

2. Gas burner according to claim 1, characterised in that the fins (3) are disposed with their lower edges (5) at a spacing from the surface of the burner pipe (2).

3. Gas burner according to claim 1 or 2, characterised in that each pair of fins (3) are arranged with side walls (7) to form a small box (8) shaft.

4. Gas burner according to one of claims 1 to 3, characterised in that the fins (3) are arranged so that their spacing from the burner pipe (2) can be varied.

5. Gas burner according to claim 1, characterised in that each pair of fins (3) are arranged to form a pocket-like body (9) which is open at the sides and at the top.

6. Gas burner according to claim 5, characterised in that the bases (10) of the pocket-like bodies (9), arranged transversely with respect to the burner pipe (2), are adapted to fit the curvature of the burner pipe (2).

7. Gas burner according to claim 5, characterised in that, the pocket-like bodies (9) are arranged longitudinally with respect to the burner pipe (2), with their bases (10) at a constant spacing from the surface of the burner pipe (2) (Fig. 8).

8. Gas burner according to claim 7, characterised in that the pocket-like bodies (9) are provided with air inlet ports (11) in their bases (10).

9. Gas burner according to one of claims 5 to 8, characterised in that the pocket-like bodies (9) are arranged at a spacing from one another corresponding to their width.

10. Gas burner according to one of claims 5 to 9, characterised in that the pocket-like bodies (9) are arranged above the areas (12) of the burner pipe (2) which are free from openings.

11. Gas burner according to one of claims 5 to 10, characterised in that the pocket-like bodies (9) are arranged together on at least one carrier (13).

12. Gas burner according to claim 11, characterised in that the pocket-like bodies (9) are arranged with their carrier (13) so as to be at a variable spacing with respect to the burner pipe (2).

13. Gas burner acording to one of claims 1 to 12, characterised in that the height of the fins (3) corresponds at most to half the diameter of the burner pipe (2).

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